Dump FramebufferSurface dataspace

For debugging, dump the dataspace details for the
FramebufferSurface. Value will be 0 (UNKNOWN) if HWC is
doing composition.
Test: adb shell dumpsys SurfaceFlinger
      Look for FramebufferSurface details.
Bug: 63146977

Change-Id: I9eb40739a616246bdac6e039270609d42eb56b59